[ECOWAR NEWSLETTER] DIFA University of Basilicata. Carmine Serio

Transcription

1 2008 DIFA University of Basilicata Carmine Serio Potenza, 15 March 2008 [ECOWAR NEWSLETTER] Preliminary Results on the Evaluation of Foreign Broadened Continuum Coefficients in the Range 250 to 600 cm 1

2 2 Dear ECOWAR people, We have now the preliminary results for the foreign broadened continuum coefficients for the range 250 to 600 cm 1. The computations have been based on a series of I BEST and REFIR PAD spectra, belonging to diverse days, acquisition modes and water vapor loads. The REFIR PAD data are from the day 9 March 2007, morning, when we observed the driest conditions during the Alps campaign (pwv=0.5 mm). The I BEST data belong to the days o 14 March 2007, the instrument was operated with the MCT detector and the cut off wave number was around 460 cm 1. The observed pwv was 5 mm (note ten times that observed for day 9!) o 10 March 2007, the instrument was operated with the DTGS detector and the cut off wave number was observed to be around 360 cm 1. The observed pwv was 1.5 mm. The results are summarized in the two figures below for the spectral ranges: Figure 1, 350 to 600 cm 1 Figure 2, 250 to 420 cm 1 These are preliminary results as said before and need to be critically reviewed and that s why I am sending them to you and some other friends and colleagues. They have been obtained with an original procedure whose main ingredients are outlined in the PDF note attached. I think that within three four weeks we should have also a draft of a possible paper to be sent for publication. Meanwhile we hope you enjoy this results which seems to be very interesting in terms of scientific merit and contents. It seems that we have demolished two past records. Looking at Fig. 2 you can see that not only our data extend beyond the old limit for which atmospheric observations are presently available (about 420 cm 1 ), they go well beyond the cut off of 333 cm 1, for which Laboratory data are available. In the segment 350 to 420 cm 1 our data are the only atmospheric observations available for now, but in the range 250 to 350 cm 1 they are simply unique. The comparison with two version of the MT_CKD continuum model allows us to derive the following considerations: Range 420 to 600 cm 1. This is the range most explored and tuned with previous field experiments. We are consistent with the models whatever the detector, instrument and water vapor load may be. This gives credibility to our novel methodology (see Fig. 1 and the attached pdf note). Range 350 to 420 cm 1, This is the range for which improvements have been hampered by a lack of field experiments. We find here discrepancies which are higher than % in some cases. Our derived coefficients are systematically lower than the model. This is confirmed with both instruments: I BEST and REFIR PAD. (see Fig. 1)

3 3 Range 250 to 350 cm 1 We have here mixed results. Although the trend is for less absorption, for some point we have a very nice agreement with MT_CKD. Next effort from us is to converge for a publication, from your side please feel free to comment on these results. That s all for now, Carmine Serio P.I. ECOWAR project.

4 Figura 1: Foreign broadened continuum coefficient (C 0 f ) for the spectral range 350 to 580 cm 1 evaluated on the basis of I BEST (Cervinia station, 2000 m) and REFIR PAD (Testa Grigia station, 3500 m) spectral observations. The calculations are compared to two versions of the MT_CKD continuum model. The I BEST data have been acquired on the day 10 March 2007 (DTGS mode, precipitable water vapor (pwv) of 1.5 mm) and on the day 14 March 2007 (MTC mode, pwv=5 mm). The REFIR PAD data refers to the day 9 March 2007, pwv=0.54 mm) 4

5 Figura 2: Foreign broadened continuum coefficient (C 0 f ) for the spectral range 260 to 450 cm 1 evaluated on the basis of I BEST (Cervinia station, 2000 m) and REFIR PAD (Testa Grigia station, 3500 m) spectral observations. The calculations are compared to two versions of the MT_CKD continuum model. The I BEST data have been acquired on the day 10 March 2007 (precipitable water vapor (pwv) of 1.5 mm). The REFIR PAD data refers to the day 9 March 2007, pwv=0.54 mm) 5